Earlier this month, 60 cattle died from probable anthrax exposure near the facilities with the newly infected cattle. One dead cow tested positive for anthrax and officials believe the disease led to the death of the others. At the time, health officials notified neighboring facilities and implementing quarantine and monitoring measures. It was the first case of anthrax in Colorado in 31 years.

None of the cattle in the original case entered the food chain.

“This is not an uncommon occurrence with anthrax because adjacent properties may also contain the anthrax spores in the soil; we certainly hoped there wouldn’t be other herds affected but this is the nature of the disease,” State Veterinarian Dr. Keith Roehr said in a statement. “We will expand our efforts onto the adjacent premises to protect the health of these cattle. At this time, all of the neighboring herds have been vaccinated for anthrax and affected herds are being treated.”

Anthrax is caused by the spore-forming bacteria Bacillus anthracis and can naturally develop in the soil.

Vaccines are available for anthrax but full immunity isn’t achieved until 7-10 days after a second dose of the vaccine is administered. Infection also can be treated with antibiotics, according to the CDA.

The CDA and the Northeast Colorado Health Department (NCHD) are performing independent investigations to monitor and control the situation, according to a statement.

The carcasses of the infected animals have been incinerated, which kills the anthrax spores.